The Compendium of Caraka 4.7.10

4.7.10

pañcadaśa koṣṭhāṅgāni; tadyathā --- nābhiśca,hṛdayaṃ ca,kloma ca,yakṛcca,plīhā ca,vṛkkau ca,bastiśca,purīṣādhāraśca,āmāśayaśca,pakvāśayaśca,uttaragudaṃ ca,adharagudaṃ ca,kṣudrāntraṃ ca,sthūlāntraṃ ca,vapāvahanaṃ ceti//

There are fifteen visceral organs; namely: navel, heart, kloman, liver, spleen, two kidneys, urinary bladder, receptacle of feces, stomach, colon, upper rectum, lower rectum, small intestine, large intestine, and omentum.